Of 41 saphenous vein aortocoronary bypass grafts from 21 patients, abnormal graft tension was judged to be present at necropsy in 6 grafts (15%) from 5 patients (24%). The abnormal tension appeared to result from the insertion of grafts too short to accomodate normal or abnormal distention of the right atrium and ventricle (graft to distal right coronary or posterior descending coronary artery) or of the pulmonary trunk (graft to left coronary system) after discontinuation of cardiopulmonary bypass or development of acute congestive cardiac failure.